A coalition of transportation advocates supported by Chicago Mayor Rahm Emanuel and Cook County President Toni Preckwinkle has recommended raising new tax money in Cook County to help pay for billions of dollars of mass transit improvements.

Launching a campaign called “Transit Future” supporters Thursday urged the Cook County board to consider creating a new “robust revenue stream” for leverage in borrowing transit money under federal financing programs.

The coalition cautioned that it is not calling for any specific taxes, but is encouraging the Cook County Board to conduct a study of options and potential revenue.

In a meeting with the Tribune’s editorial board, coalition leaders said that the board could potentially raise property, sales, or gasoline taxes for the local share. The money would help pay for such big-ticket projects in Chicago and Cook County as the long-sought extension of the CTA’s Red Line to the far South Side.

The Red Line extension and other billion-dollar projects like suburb-to-suburb Metra STAR Line have languished in recent years because federal funding for major transit endeavors has all but disappeared.

“Creating a local, matching revenue stream can unlock billions in federal and other funding for the kinds of transit projects that can make our region more livable, economically competitive, and environmentally sustainable,” said Jacky Grimshaw, vice president for policy at the Center for Neighborhood Technology, a Chicago-based urban research group and coalition partner.

The coalition’s campaign comes on the heels of a Northeastern Illinois Public Transit Task Force report released Monday which concluded that current funding levels are insufficient to maintain current service, much less expand it.

The Regional Transportation Authority has determined that the CTA, Metra and Pace together will need $33.4 billion over the next 10 years to keep the current transit system in good condition. Of that amount, $20 billion is needed to pay for a backlog of track and equipment replacement, bridge repairs and station improvements.

The Transit Future coalition said this can be done by tapping an Obama administration program called America Fast Forward and other financing tools at the federal level.

One aspect of the Fast Forward program includes low-cost lending under the Transportation Infrastructure Finance and Innovation Act (TIFIA) to finance transportation projects. But local money is needed as leverage for the federal loans.

The transit task force on Monday laid out a menu of funding options that it recommended by considered. Other potential local revenue sources include an additional parking tax or extra fee on vehicle registrations.

In addition to Emanuel and Preckwinkle, the Transit Future coalition said it is supported by a variety of transportation advocates, business and civic groups, Chicago aldermen, and labor unions.

The coalition brought former Los Angeles Mayor Antonio Villaraigosa and former Santa Monica Mayor Denny Zane to Chicago Thursday to describe how a similar campaign helped provide $40 billion worth of new and expanded transit in Los Angeles County.

Even though the task force report called for a more regional approach to transit planning and setting project priorities, members said focusing on Cook County needs alone would not fuel the parochialism and city-suburban rivalry that had often deadlocked the RTA.

But Grimshaw said Cook County is the logical place to start the campaign because it has the most pressing needs. Other counties in the RTA region could copy the campaign, she said.